Holding is about keeping a constant low temp such as in a cambrio or insulated cooler and resting is letting it go down to something closer to room temp on its own, and quicker. So I don't consider them the same technique at all, even if both activities help.
Meat kept at 140-170 for 2 hours wasn't rested. It was held fairly constant! Meat allowed to sit on the kitchen counter for 15-30 minutes before slicing didn't "hold" a temperature, it got cooler and cooler and cooler by ambient temp overpowering it.
Yes they are closely related since neither is "actively" cooking the food, by letting the meat do anti-cooking things prior to being cut up.